Currently, in doors of many automobiles, so-called power windows are adopted. A power window is provided with a window regulator which raises and lowers a window glass by electric power, and a window regulator is constituted by comprising a carrier plate which holds the window glass, and a guide rail which extends in a raising and lowering (up and down) direction, and which moves the carrier plate in a raising and lowering (up and down) direction by the operation of a motor.
It is preferable for the carrier plate to be made of resin, because it is possible to attempt to design for mass reduction of the vehicle, and to increase cost efficiency. Among these, it is preferable for the carrier plate to be made of a polyacetal (POM) resin, because it is excellent in mechanical characteristics, thermal characteristics, slidability, moldability, and the like.
Patent Document 1 discloses a carrier plate made of polyacetal resin reinforced by a thickened reinforcing portion or the like, constituted by comprising a plate-shaped main body, and a reinforcing portion.
Incidentally, the carrier plate is mounted in a space between a door outer panel and a door inner panel in a door main body constituted by comprising a door outer panel and a door inner panel. The volume of this space is limited, moreover, members other than the carrier plate are also accommodated in this space. In addition, the carrier plate is a relatively large resin molded article, occupying a length of about 10 cm in both the longitudinal and transverse directions.
Hence, when molding a plate-shaped molded article from a polyacetal resin composition, there is demand for increasing the flatness of the resin molded article, such that it can be suitably accommodated in a limited space without interfering with other members, and increasing the dimensional stability while suppressing shrinkage ratio anisotropy due to molding as much as possible. Furthermore, in addition to creep resistance and impact strength, from the viewpoint of the quality consistency of the molded article when molding, there is high demand for color stability when remaining in the molding machine. If the color is unstable when remaining in the molding machine, molding condition dependency arises, whereby it may not be possible to consistently maintain a stable product quality.    Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2004-314819